The Pololu MinIMU-9 is an inertial measurement unit (IMU) that packs an L3G4200D 3-axis gyro and an LSM303DLM 3-axis accelerometer and 3-axis magnetometer onto a tiny 0.9″ × 0.6″ board. An I²C interface accesses nine independent rotation, acceleration, and magnetic measurements that can be used to calculate the sensor’s absolute orientation.